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Current Research and Scholarly Interests

As a professor in the Medical Center Line, my primary investigative interest has been in clinical neuroradiology. This encompasses spinal cord and spine disease, degenerative and demyelinating diseases of the central nervous system, strokes and infarction, and chronic epilepsy syndromes. Facial and head and neck vascular malformations and hemangiomas have been a focus of interest for many years, with collaborative projects involving dermatology and functional restoration services.

Clinical Trials

The purpose of this study is to determine the value of novel non-invasive medical imaging
methods for detecting the spread of head and neck squamous cell carcinoma to the lymph nodes
in the neck by comparing their results to findings at the time of surgery.

Stanford is currently not accepting patients for this trial.For more information, please contact Quynh-Thu Le, (650) 498 - 6184.

All Publications

Abstract

Virtual histology intravascular ultrasound (VH IVUS) is valuable for estimating minimal lumen diameter and plaque characterization. The clinical use of IVUS in carotid intervention is not well characterized. We aim to evaluate the role of IVUS in carotid plaque characterization and determine whether it could be predictive of procedure-related microemboli.From July 2010, patients with severe carotid stenosis who underwent elective carotid stenting procedures were prospectively enrolled. IVUS evaluation was performed before stent placement. Patient demographics, comorbidities, and preoperative images were recorded. Comparison of pre- and postoperative diffusion-weighted magnetic resonance images was used to identify the number of procedure-related microemboli. IVUS-derived minimal lumen diameter and vessel wall plaque characteristics were collected. Univariate and multivariate logistic regressions were used to search for associations between IVUS-derived VH data and incidence of microemboli.A total of 38 high-risk patients receiving carotid stenting were enrolled. Among them, 25 patients had type I aortic arches and 17 of the patients were symptomatic (preoperative stroke or transient ischemic attack). VH IVUS data did not show strong associations with microemboli, however, a trend was found between the area of fibrous tissue and median or more incidence of microemboli (P = .099). IVUS-defined vessel diameter maximum was associated with median or more incidence of microemboli (P = .042). In addition, median or more incidence of microemboli showed trends with proximal common carotid artery calcification (P = .056) and with being over the age of 80 (P = .06). Contralateral carotid occlusion or high-grade stenosis was associated with postoperative contralateral microemboli (P = .036).We demonstrate that periprocedural carotid IVUS is clinically feasible. VH IVUS may be helpful in better understanding plaque morphology and determining optimal stent placement. However, its use in predicting microembolization remains limited.

Abstract

Subclinical microembolization identified on diffusion-weighted magnetic resonance imaging is recognized as an important outcome measure for carotid revascularization procedures. It is generally believed that arch manipulation is the primary reason for developing microemboli in the contralateral hemisphere during carotid artery stenting. However, we identified three patients who developed postprocedure microemboli of the contralateral hemisphere despite a known chronic contralateral internal carotid artery occlusion. Our cases highlight that ipsilateral microemboli may be an underappreciated but an important source of contralateral lesions through patent intracranial collateral pathways.

Abstract

Randomized controlled trials have shown that periprocedural rates of stroke and death are higher with carotid artery stenting (CAS) than with carotid endarterectomy (CEA) in the treatment of carotid artery stenosis. Diffusion-weighted magnetic resonance imaging (DW-MRI) has shown higher rates of clinically silent new ischemic brain lesions when CAS is performed as compared with CEA. The Silk Road Medical Embolic PROtectiOn System: First-In-Man (PROOF) Study is a single-arm first-in-man study using the MICHI Neuroprotection System (Silk Road Medical Inc, Sunnyvale, Calif), a novel transcervical access and cerebral embolic protection system. This system enables stent implantation under controlled blood flow reversal of the carotid artery, also known as Flow Altered Short Transcervical Carotid Artery Stenting (FAST-CAS).Between March 2009 and February 2010, a total of 44 subjects were enrolled into the study. The primary composite endpoint was major stroke, myocardial infarction, or death within 30 days. Forty-three patients (97.7%) completed the study through the 30-day endpoint. One patient was lost to follow-up. In a subgroup of consecutive subjects, DW-MRI examinations were performed preprocedure and within 24 to 48 hours after the stent implantation. Blinded independent neuroradiologists reviewed all DW-MRI studies and confirmed the absence or presence of new ischemic brain lesions.All enrolled patients were successfully treated, and no major adverse events were seen through the follow-up period. Thirty-one subjects had DW-MRI examinations. Of these, five patients (16%) had evidence of new ischemic brain lesions but no clinical sequelae. Transient intolerance to reverse flow was reported in 9% of cases, but in all cases, a stent was successfully placed, and the intolerance was managed by minimizing the duration of reverse flow during the procedure.In this first-in-man experience, FAST-CAS using the MICHI Neuroprotection System was shown to be a safe and feasible method for carotid revascularization. DW-MRI findings suggest controlled reverse flow provides cerebral embolic protection similar to that seen with CEA.

Abstract

Subclinical microemboli documented on diffusion-weighted magnetic resonance imaging (DWI) are common following carotid artery stenting (CAS) procedures despite absence of neurological symptoms. This study was to evaluate risk factors predictive of microemboli in patients undergoing protected CAS with a distal embolic protection device. All CAS patients who received pre- and postprocedural magnetic resonance imaging (MRI) evaluations for carotid interventions at a single academic institution from July 2004 to December 2008 were examined. Microemboli were defined by new hyperintensities on postoperative DWI with corresponding decreased diffusion. Risk factors including patient demographics, medical comorbidities, clinical symptoms, lesion morphologies, and perioperative information were examined, and logistic regression analyses were utilized to determine predictors of CAS-related microemboli. A total of 204 patients underwent carotid interventions (76 CAS and 128 carotid endarterectomies) during the study period; 167 of them, including 67 CAS patients, received both preoperative and postoperative MRIs. Among those who underwent protected CAS, the incidence of microemboli was 46.3% despite a relative low incidence of associated neurological symptoms (2.9%). Univariate and multivariate regression analyses showed that date of procedure (odds ratio [OR] 30.6 and p?=?0.019) and preoperative transient ischemic attack symptoms (OR 9.24 and p?=?0.009) were independent predictors of developing postoperative changes on DWI in the ipsilateral hemisphere, and age >76 years was predictive of having new lesions on DWI in the contralateral hemisphere (OR 6.11 and p?=?0.026). Our study underscores that certain risk factors are significantly associated with CAS-related microemboli and that physician experience and patient selection are essential in improving outcome of CAS procedures.

Abstract

Cerebral embolisation constitutes the main source of complications during transfemoral carotid artery stenting (CAS) and is associated with a high incidence of silent brain infarction. The goal of this study is to evaluate the incidence of new ischaemic cerebral lesions following transcervical CAS with carotid flow reversal for neuroprotection.Thirty-one consecutive patients underwent transcervical CAS with carotid flow reversal. A stroke scale and diffusion-weighted magnetic resonance imaging (DW-MRI) were performed within 24 h before and after the procedure. DW-MRI studies were compared blindly by two independent neuroradiologists. New hyper-intense DW signals were interpreted as ischaemic infarcts. The progress of all patients was followed for at least 30 days following intervention.All procedures were technically successful. Nineteen (61%) patients were symptomatic Mean carotid flow reversal time was 22 min. There were no major adverse events at 30 days. All patients remained neurologically intact without increase in the stroke scale. Thirty subjects had paired DW-MRI studies. Post-procedural DW-MRI ischaemic infarcts were found in four (12.5%) patients, all ipsilateral to the treated hemisphere and asymptomatic. During follow-up, all stents remained patent and all patients remained stroke-free.These data suggest that transcervical carotid stenting with carotid flow reversal carries a low incidence of new ischaemic infarcts, significantly lower than that reported with transfemoral CAS. The transcervical approach with carotid flow reversal may improve the safety of CAS and has the potential to produce results comparable to those of carotid endarterectomy.

Abstract

Superficial siderosis (SS) of the central nervous system is a rare condition caused by chronic subarachnoid hemorrhage. Clinical manifestations typically include sensorineural hearing loss and cerebellar ataxia. Recurrent episodic encephalopathy in the setting of SS has not been reported. We describe a unique case of SS in a 67-year-old man with an 8-year history of episodic encephalopathy associated with headache and vomiting. The patient also had a history of progressive dementia, ataxia, and myelopathy. A diagnosis of superficial siderosis was made after magnetic resonance gradient-echo images showed diffuse hemosiderin staining over the cerebellum and cerebral convexities. No intracerebral source of hemorrhage was identified. The patient therefore underwent gadolinium-enhanced spinal MRI which suggested a possible vascular malformation. A therapeutic laminectomy subsequently confirmed an arteriovenous fistula which was resected. In SS, there are often long delays between symptom onset and definitive diagnosis. Early identification is facilitated by magnetic resonance imaging with gradient-echo sequences. When no source of hemorrhage is identified intracranially, then total spinal cord imaging is indicated to assess for an occult source of hemorrhage as occurred in our case.

Abstract

Subclinical microemboli on diffusion-weighted magnetic resonance imaging (DWI) have been identified immediately following carotid revascularization procedures, but the clinical significance and long-term effects are largely unknown. The purpose of this study was to evaluate long-term radiographic outcomes of these DWI lesions.Patients who underwent perioperative magnetic resonance imaging (MRI) evaluations for carotid interventions at a single institution from July 2004 to December 2008 were evaluated, particularly those who had additional follow-up MRI. DWI with apparent diffusion coefficient (ADC), fluid-attenuated inversion recovery (FLAIR), and T2-weighted MRI images were compared to determine long-term effect of microemboli.One-hundred sixty-eight consecutive patients (68 carotid artery stenting [CAS] and 100 carotid endarterectomy [CEA]) who received perioperative MRI were included. All CAS were performed with an embolic protection device. The incidence of microemboli was significantly higher in the CAS group than the CEA group (46.3% and 12%, respectively, P < .05) despite a relative low incidence of procedure-associated neurologic symptoms in both groups (2.9% vs 2%). Thirty patients (16 CAS and 14 CEA) who had follow-up MRI were further analyzed and a total of 50 postoperative DWI lesions (mean size 46.57 mm(2); range 16 to 128 mm(2)) were identified among them. During a mean MRI follow-up of 10 months (range, 2 to 23 months), residual MRI abnormalities were only identified in DWI lesions larger than 60 mm(2) on postoperative MRI and on postoperative FLAIR images (n = 5, P < .001). The CEA group had fewer but larger ipsilateral distributed emboli (total 12 lesions, mean 79 mm(2)) compared with the CAS group (total 38 lesions, mean 27.5 mm(2), P < .05).The majority of microemboli do not have long-term radiographic sequelae. Size and hyperintensity on postoperative FLAIR are predictive of residual brain structure abnormality, and further neurocognitive evaluations are warranted.

Abstract

We have previously demonstrated a 70% incidence of microemboli on diffusion weighted magnetic resonance imaging (DW-MRI) following carotid angioplasty and stenting (CAS). The purpose of this study is to compare the incidence of microemboli in two distinct time periods when procedural modifications were implemented into a CAS program.Following a retrospective quality review of our CAS cohort (n = 27) from November 2004 through April 2006 (period 1), we enrolled patients (n = 20) from May 2006 through February 2008 (period 2) undergoing CAS into a prospective cohort that included obtaining pre- and postprocedure DW-MRI exams. Procedural modifications during period 2 included the preferential use of closed-cell systems (60% vs 0% in period 1), early heparinization at the initiation of arterial access, and elimination of an arch angiogram. The hospital records of these 47 patients were reviewed; symptoms, comorbidities, lesion characteristics, periprocedural information, and postoperative outcomes were collected. The incidence and location of acute, postprocedural microemboli were determined using DW-MRIs.Twenty (74%) CAS patients from period 1 and seven (35%) patients from period 2 demonstrated acute microemboli on postprocedural DW-MRI (P = .02). The mean number of microemboli in period 1 was 4.1 +/- 5.3 vs 1.5 +/- 2.7 during period 2 (P = .04). Two of the 27 patients (7.4%) during period 1 experienced temporary neurologic changes that resolved within 36 hours. None of the patients during period 2 exhibited any neurologic changes. Patient demographics, comorbidities, and presenting symptoms were similar between the two groups except for smoking prevalence, female presence, and obesity (BMI > 30). Period 2 patients when compared with period 1 had more technically challenging anatomy with more calcified lesions (68% vs 27%), longer lesions (15.9 mm vs 8.2 mm), and higher incidence of ulceration (55% vs 27%) (all P < .04).Despite successful performance of 47 consecutive CAS procedures without permanent neurologic sequelae, significant reductions in periprocedural embolic events as identified via DW-MRI lesions may be achieved through implementation of quality improvement measures identified through continuous outcome analysis. The long-term neurologic benefits associated with reduced subclinical neurologic events remains to be determined.

Abstract

The relative safety of percutaneous carotid interventions remains controversial. Few studies have used diffusion-weighted magnetic resonance imaging (DW-MRI) to evaluate the safety of these interventions. We compared the incidence and distribution of cerebral microembolic events after carotid angioplasty and stenting (CAS) with distal protection to standard open carotid endarterectomy (CEA) using DW-MRI.From November 2004 through August 2006, 69 carotid interventions (27 CAS, and 42 CEA) were performed in 68 males at a single institution. Pre- and postprocedure DW-MRI exams were obtained on each patient undergoing CAS and the 20 most recent CEA operations. These 46 patients (47 procedures as one patient underwent bilateral CEAs in a staged fashion) constitute our study sample, and the hospital records of these patients (27 CAS and 20 CEA) were retrospectively reviewed. The incidence and location of acute, postprocedural microemboli were determined using DW-MRIs and assessed independently by two neuroradiologists without knowledge of the subjects' specific procedure.Nineteen CAS patients (70%, 95% confidence interval [CI]: 42%-81%) demonstrated evidence of postoperative, acute, cerebral microemboli by DW-MRI vs none of the CEA patients (0%, 95% CI: 0%-17%) (P < .0001). Of the 19 CAS patients with postoperative emboli, nine (47%) were ipsilateral to the index carotid lesion, three (16%) contralateral, and seven (36%) bilateral. The median number of ipsilateral microemboli identified in the CAS group was 1 (interquartile ranges [IQR]: 0-2, range 0-21). The median number of contralateral microemboli identified in the CAS group was 0 (IQR: 0-1, range 0-5). Three (11%) CAS patients experienced temporary neurologic sequelae lasting less than 36 hours. These patients suffered 12 (six ipsilateral and six contralateral), 20 (19 ipsilateral and one contralateral), and zero microemboli, respectively. By univariate analysis, performing an arch angiogram prior to CAS was associated with a higher risk of microemboli (median microemboli 5 vs none, P =.04)Although our early experience suggests that CAS may be performed safely (no permanent neurologic deficits following 27 consecutive procedures), cerebral microembolic events occurred in over two-thirds of the procedures despite the uniform use of distal protection. Open carotid surgery in this series seems to offer a lower risk of periprocedural microembolic events detected by DW-MRI.

Abstract

To determine risk factors predictive of microemboli found on diffusion-weighted magnetic resonance imaging (DW-MRI) following carotid angioplasty and stenting (CAS) with distal protection and carotid endarterectomy (CEA).A retrospective review was conducted of all carotid interventions at a single institution between 2004 and 2006. In that time frame, 64 carotid interventions (34 CAS, 30 CEA) were performed in 63 male patients (mean age 69.5 years, range 52 to 91) with DW-MRI scans available for review. Patient characteristics, including age, gender, smoking history, diabetes mellitus, hypertension, hyperlipidemia, obesity (body mass index >30), coronary artery disease (CAD), chronic obstructive pulmonary disease, peripheral vascular disease, and atrial fibrillation, were documented. For the CAS patients, anatomical and procedural characteristics, including fluoroscopy time, contrast volume, performance of an arch angiogram, and lesion anatomy, were recorded. Bivariate analyses were performed to determine which parameters were associated with the occurrence of acute postprocedural microemboli found on DW-MRI by 2 blinded neuroradiologists.Twenty-four (71%) of the 34 CAS patients and 1 (3%) of the 30 CEA patients demonstrated new cerebral microemboli postoperatively. In the bivariate analyses of all patient, anatomical, and procedural characteristics, only a history of CAD was associated with an increased risk of microemboli; 20 (80%) of the 25 patients who had postprocedure microemboli had CAD compared to 18 (46%) of 39 patients without microemboli (p=0.007). Twenty (53%) of the 38 (59%) patients with CAD developed microemboli compared to 5 (19%) of the 26 patients without CAD (p=0.007). All other patient, procedural, and anatomical characteristics were not found to be independent risk factors predictive of postprocedure microemboli.CAS with distal protection carries a significantly greater risk for developing new microemboli compared to CEA. Of all the risk factors analyzed, only a history of CAD emerged as an independent risk factor for the development of microemboli following carotid intervention. This finding may influence the decision to perform CAS in patients deemed high risk solely due to the presence of CAD.

Abstract

Studies imposing rigorous control over lifetime alcohol intake have usually not found smaller hippocampal volumes in persons with posttraumatic stress disorder. Because the majority of negative studies have used adolescent samples, it has been suggested that chronicity is a necessary condition for such findings. To test the hypothesis that a smaller hippocampus in PTSD is unrelated to comorbid alcoholism or to chronicity, this study estimated hippocampal volume in a relatively large group (N=99) of combat veterans in which PTSD, lifetime alcohol abuse/dependence, and Vietnam versus Gulf War service were crossed. In subjects with histories of alcoholism, unadjusted hippocampal volume was 9% smaller in persons with PTSD than in those without PTSD. In nonalcoholic subjects, the PTSD-related difference in hippocampal volume was 3%. The failure to observe a strong association between PTSD and hippocampal volume in nonalcoholic subjects was not ascribable to younger age, reduced PTSD chronicity, or lower PTSD symptom severity. The possibility that smaller hippocampal volume is limited to groups in which PTSD is compounded by comorbid alcoholism is not necessarily incompatible with results suggesting a smaller hippocampus is predispositional to PTSD. Further examination of the role of alcoholism and other comorbid conditions in studies of brain structure and function in PTSD appears warranted.

Abstract

Magnetic resonance imaging is the imaging method of choice in most diseases of the spinal canal and cord. Many pulse sequences are available, and in this era of increased expectations and diminishing resources, a practical approach to the most efficient spine imaging is needed. Our strategy is a series of protocols tailored to the particular area of the spine and the disease process suspected.

Abstract

CNS amyloidomas are rare. We describe a 51-year-old man with isolated amyloidomas in the cerebral white matter and in the pons. CT and MR imaging showed a heterogeneous, enhancing mass in the deep cerebral white matter. A second, much smaller linear serpiginous lesion was present in the pons.

Abstract

To assess the quality of brain computed tomographic (CT) studies obtained with a four-channel multi-detector row CT scanner compared with those obtained with a single-detector row CT scanner.Forty-seven patients referred for brain CT were imaged with both single- and multi-detector row scanners. Single-detector row CT images were acquired by using a 5-mm-collimated beam in the transverse mode. Multi-detector row CT images were acquired in four simultaneous 2.5-mm-thick sections, which were combined in projection space to create two contiguous 5-mm-thick sections. Two neuroradiologists blinded to the acquisition technique independently evaluated the CT image pairs, which were presented in a stacked mode on two adjacent monitors. Each study was graded by using a five-point scale for posterior fossa artifact, overall image quality, and overall preference.Multi-detector row CT studies were acquired 1.8 times faster than single-detector row CT studies (0.92 vs 0.52 section per second). Multi-detector row CT posterior fossa artifact was less than single-detector row CT posterior fossa artifact in 87 (93%) of 94 studies. Overall preference was expressed for multi-detector row CT in 84 (89%) of 94 studies. The differences in mean posterior fossa artifact scores (P

Abstract

Overall prognosis of nonpenetrating traumatic brain hemorrhage may be predicted by neurologic function days after insult. The relationship between immediate function and outcome has not been examined for infratentorial traumatic brain hemmorhage (iTBH) identified on computed tomographic (CT) scan. Given the severity of brain stem injury, it is conceivable that immediate function may be predictive.A retrospective review of 1,500 brain injuries occurring at our institution identified 18 patients (1.2%) with iTBH on CT scan (eight brain stem, five cerebellum, five both). Demographics, supratentorial injuries, and outcome at 6 months (Glasgow Outcome Scale) were recorded.Initial Glasgow Coma Scale (GCS) in 11 patients was less than 5 (group I). Seven patients had GCS scores greater than or equal to 6 (group II). Nine patients in group I either died or were vegetative. In group II, one died; none were vegetative (p < 0.02). Regression analysis demonstrated a strong correlation between initial GCS and Glasgow Outcome Scale scores at 6 months for all patients (p < 0.001).We conclude that initial GCS score may be predictive of long-term outcome in patients with CT scan evidence of iTBH-a relationship to be explored further for prognostic information.

Abstract

Sonography, CT, and MR imaging are commonly used to screen for neonatal intracranial ischemia and hemorrhage, yet few studies have attempted to determine which imaging technique is best suited for this purpose. The goals of this study were to compare sonography with CT and MR imaging prospectively for the detection of intracranial ischemia or hemorrhage and to determine the prognostic value(s) of neuroimaging in neonates suspected of having hypoxic-ischemic injury (HII).Forty-seven neonates underwent CT (n = 26) or MR imaging (n = 24) or both (n = 3) within the first month of life for suspected HII. Sonography was performed according to research protocol within an average of 14.4 +/- 9.6 hours of CT or MR imaging. A kappa analysis of interobserver agreement was conducted using three independent observers. Infants underwent neurodevelopmental assessment at ages 2 months (n = 47) and 2 years (n = 26).CT and MR imaging had significantly higher interobserver agreement (P < .001) for cortical HII and germinal matrix hemorrhage (GMH) (Grades I and II) compared with sonography. MR imaging and CT revealed 25 instances of HII compared with 13 identified by sonography. MR imaging and CT also revealed 10 instances of intraparenchymal hemorrhage (>1 cm, including Grade IV GMH) compared with sonography, which depicted five. The negative predictive values of neuroimaging, irrespective of technique used, were 53.3% and 58.8% at the 2-month and 2-year follow-up examinations, respectively.CT and MR imaging have significantly better interobserver agreement for cortical HII and GMH/intraventricular hemorrhage and can reveal more instances of intraparenchymal hemorrhage compared with sonography. The absence of neuroimaging findings on sonograms, CT scans, or MR images does not rule out later neurologic dysfunction.

Abstract

Neuropathological studies use the presence of mammillary body (MB) pathology as a cardinal, diagnostic feature of Wernicke's encephalopathy (WE) in neuropsychiatric diseases, most notably alcoholism. Although Korsakoffs Syndrome (KS), which is marked behaviorally by dense global amnesia, is a typical sequela of WE, it remains controversial whether these two conditions necessarily co-occur and whether MB pathology is therefore a diagnostic requisite for KS.We investigated these issues by examining, in vivo, 24 nonamnesic alcoholics (ALC), 5 amnesic alcoholics (KS), and 51 normal controls with three-dimensional MRI and memory testing. MB volume was determined from successive, 1 mm thick slices.The ALC group had significantly smaller MB volumes bilaterally (mean = 54.5 +/- 22.0 mm3) than controls (mean = 66.3 +/- 17.1 mm3), and the KS group had even smaller MB volumes than the ALC group (mean = 20.7 +/- 14.8 mm3). Only 2 ALC patients met historical clinical criteria for past WE, and their MB volumes were well within range of the remaining 22 ALC patients. Although all five KS patients met historical clinical criteria for WE, three KS did not have accompanying dementia and had the same degree of MB volume loss as the ALC; the remaining two KS had accompanying dementia and MB volumes half the volume of the ALC group and of KS patients without dementia.These findings provide volumetric in vivo evidence that: (1) MB volume deficits do occur in alcoholics without amnesia, although these deficits are not present in ail such alcoholics; (2) greater MB volume deficits are present in alcoholics with clinically detectable amnesia or dementia; (3) MB shrinkage is related to severity of cognitive and memory dysfunction, which suggests a continuum of MB pathology in chronic alcoholism to KS; and (4) the presence of WE in all of the KS patients and in the two ALC patients with the greatest long-term declarative memory deficit supports the possibility of an additional and unique pathology distinguishing nonamnesic and amnesic alcoholism.

Abstract

This study presents baseline and 3-month follow-up motor and neuropsychological data for 22 patients with Parkinson's disease (PD) who underwent anatomically guided unilateral posterior ventral pallidotomy (PVP). Postsurgical improvements were seen in psychomotor speed, fine motor accuracy, and dyskinesia, whereas grip strength decreased on the side contralateral to the surgery. No change was detected in overall level of cognitive functioning, nor were changes demonstrated in memory, language, or working memory when the entire sample of patients was evaluated. When the group was divided on the basis of side of surgery, patients with left-sided pallidotomies showed a decline in verbal fluency. Patients and caregivers reported improvement in psychosocial functioning. These initial findings of improved motor performance and largely unaffected cognitive functions are consistent with results obtained with functional PVP and provide support for the use of anatomically guided posterior ventral pallidotomy in the treatment of motor symptoms of PD.

Abstract

We present the clinical, imaging, and neuropathologic data for a family with an autosomal dominant, nonhypertensive, progressive cerebral arteriopathy and leukoencephalopathy. Clinical presentation was characterized by progressive dementia, gait abnormalities, and, in some, Parkinson-like symptoms. MR abnormalities, consisting of white matter T2 hyperintensities and cystic-appearing T1 hypointensities, were present in seven family members. The basal ganglia also showed cystic abnormalities. Neuropathologic examination in two cases revealed numerous lacunar infarctlike lesions, extensive demyelination, and widespread hyalinization of arteriolar walls with karyolysis and granular deposits within the media. These findings appear to constitute further evidence of a genetically determined arteriopathic leukoencephalopathy.

Abstract

Methodological issues have limited neuroimaging studies of cerebellar structures. In this article we describe a method that addresses some of these limitations and phantom studies that examine the validity of the image manipulations. We compared volumes derived from 3D Spoiled Gradient Recalled Acquisition MR images sliced with respect to three different alignment methods: one based on cerebellar landmarks, another on cerebral landmarks and a third on the plane of acquisition. Examination of coefficients of variation, coefficients of error and convergent validity suggests that although regional cerebellar volumes based on cerebellar landmarks provide the best estimates of the true volumes, observed differences between volume measurements from alignments based on cerebellar or cerebral landmarks were generally not significant and were inconsequential. In this case, the measure was improved with alignment along local, relevant cerebellar landmarks. A set of phantom experiments showed that realignment, reslicing and interpolation in 3-dimensional image processing exerted, at most, trivial distortion on the estimates of actual object volumes.

Abstract

Mammillary body and cerebellar atrophy have been described as postmorten neuropathologic markers of Korsakoff's syndrome. This study examined whether shrinkage in the mammillary bodies and cerebellum is present consistently in amnesic chronic alcoholics during life and whether the degree of abnormality in these patients differs from that in nonamnesic alcoholic and healthy controls. The severity of shrinkage in the mammillary bodies, cerebellar hemispheres, and cerebellar vermis visualizable on MRI scans was rated on a three-point scale in 33 chronic nonamnesic alcoholics, 9 amnesic alcoholics, and 20 healthy controls. Although both alcoholic groups showed significant mammillary body and cerebellar shrinkage relative to controls, the two patient groups did not differ from each other. Furthermore, four of eight amnesic patients in our sample did not demonstrate clinically significant mammillary body atrophy. These results suggest that alcoholism is associated with mammillary body and cerebellar tissue volume loss but do not provide evidence that these markers distinguish accurately between amnesic and nonamnesic patients. In addition, they suggest that visualizable mammillary body atrophy is not necessary for the development of amnesia in alcoholic patients.

Abstract

To assess the usefulness of ultrasound (US), computed tomography (CT), and magnetic resonance (MR) imaging in the detection of intracranial hemorrhage and ischemia in newborns.Seventy-six neonates who underwent US within 72 hours of CT or MR examination were studied. Four observers rated images for the presence of germinal matrix hemorrhage (GMH), intraventricular hemorrhage (IPH), extraaxial hemorrhage, and hypoxic-ischemic encephalopathy.In 39% of neonates, CT and MR imaging provided greater confidence than US for the diagnosis or exlusion of neonatal ischemia or hemorrhage. Kappa analysis revealed significantly better interobserver agreement with CT than with US for the detection of GMH, IVH, IPH, and cortical infarction or ischemia (P

Abstract

To determine the economic effect of endovascular therapy in conjunction with surgery for cerebral arteriovenous malformations.Twenty-five patients with arteriovenous malformations treated with embolization and surgical excision or embolization alone were compared with reported results in 475 patients who underwent surgery only. Respective mean morbidity and mortality rates were calculated and a cost-effectiveness analysis was performed in terms of costs of hospitalization, professional fees, and other direct procedural and indirect costs. Quality-adjusted life-years saved were also calculated.The net effective treatment cost per cure was $71 366 (in 1992 dollars) for embolization and surgery compared with $78 506 for surgery alone. This resulted in a 9% average savings per treated patient. Cost per quality-adjusted life-year calculations resulted in a cost of $6734 for embolization and surgery and $9814 for surgical treatment alone, with savings as high as 34% when endovascular therapy was used.Endovascular therapy in conjunction with surgery resulted in significant economic benefits for treatment of cerebral arteriovenous malformations.

Abstract

To observe and quantify white matter hyperintensities on MR images in adults with schizophrenialike symptoms who had had congenital rubella, in order to elucidate the neuropathologic sequelae of this perinatal viral infection and to explore the potential relationship of these lesions to schizophrenia.Eleven deaf adult patients with documented prenatal rubella virus infection and schizophrenialike symptoms were compared with 19 age-matched patients with early-onset schizophrenia who did not have congenital rubella and with 18 age-matched control subjects. All MR images (obtained at 1.5 T) were evaluated by a neuroradiologist who was blinded to diagnosis and were rated for white matter lesions on a five-point scale: 0 = no lesions; 1 = 1 lesion less than 1 mm in diameter; 2 = 1 to 4 lesions 1 mm or greater; 3 = 5 to 10 lesions; 4 = more than 10 lesions or a single lesion more than 1 cm in diameter. In addition, the white matter hyperintensities were volumed objectively with a manual threshold technique.Ratings of white matter lesions were significantly higher in the rubella patients than in the control subjects: 6 of the 11 patients had ratings greater than 1 compared with 1 of the 18 control subjects and none of the 19 schizophrenic patients. Also, MR images in five rubella patients received ratings at the highest end of the scale of abnormality (3 or 4). The white matter hyperintensities were characterized as bilateral T2 signal hyperintensities in periventricular and subcortical regions, punctate or linear in shape; they were observed predominantly in parietal lobes.This quantitative MR study of adult rubella patients disclosed abnormal white matter lesions that may correspond to neurovascular lesions known neuropathologically. They do not appear to be directly related to schizophrenialike symptoms.

Abstract

Brain morphology was quantified with magnetic resonance imaging (MRI) in adult patients with congenital rubella who also had schizophrenialike symptoms. MRIs were compared with those of adult early-onset schizophrenic patients without congenital rubella and age-matched healthy control subjects. The rubella patients had significantly smaller intracranial volumes and shorter stature than the schizophrenic patients or the controls; however, both patient groups had smaller cortical gray matter, but not white matter, volumes than the control group, even when the MRI volumes were corrected for head size and age. In addition, both patient groups showed significant enlargement of the lateral ventricles but not cortical sulci when compared with expected values of normal adults of the same age and head size. Overall, the pattern of dysmorphology was identical in the rubella and the schizophrenic groups. The observations in the rubella group are consistent with a developmental lesion that limits full brain growth, with the small intracranial volume due at least in part to a severe cortical gray matter volume deficit. Thus, the brain dysmorphology of congenital rubella may provide an instance of prenatal viral infection that models the schizophrenic pattern and provides indirect support for a developmental hypothesis of the neuropathogenesis of schizophrenia.

Abstract

We report two cases in which combined surgical clipping and endovascular coils have been used to treat intracranial aneurysms. In one case, a 59-year-old woman with multiple episodes of subarachnoid hemorrhage had an anterior communicating artery aneurysm, which was initially treated with coils and then clipped to occlude the aneurysm securely. In the second case, a broad-based cavernous aneurysm could not be completely surgically occluded, but surgical clipping did decrease the aneurysm neck size, allowing it to be successfully treated with coils.

Abstract

To report initial clinical experience with stent placement in the cerebrovascular circulation.Four patients underwent arterial or venous stent placement. Two patients had cervical internal carotid artery dissections, with aneurysms and stenoses of the distal cervical carotid artery. Two patients had venous occlusive disease involving the major dural sinuses, with substantial pressure gradients across the stenoses.Immediately after stent placement, the true arterial lumina returned to normal diameter and both carotid aneurysms were more than 90% occluded. Follow-up angiography demonstrated continued improvement in the arterial aneurysms. Both patients with dural sinus venous occlusive disease showed substantial improvement of the sinus stenoses and substantial reversal of the pressure gradients after venous stent placement. At follow-up, these patients have done well.This preliminary experience suggests there may be a role for stents in the management of arterial and venous cerebrovascular disease, including carotid artery dissection and venous occlusive disease.

Abstract

To evaluate mechanically detachable coil designs capable of controlled and instantaneous release within an aneurysm or vascular space.Three mechanically detachable coil designs, clamped ball, looped ribbon, and interlocking cylinder, were evaluated using in vitro and in vivo testing to study reliability of coil release, retractability, and coil behavior in a microcatheters. In vitro tests were performed using a glass side-wall aneurysm model and conventional microcatheters. In vivo experiments in rabbits included aneurysm models (side-wall and bifurcation) and arterial occlusions (carotid and renal).All three designs deployed coils easily and were able to retract coils after partial deployment. Motion was seen in previously released coils and in the catheter when using the clamped ball and looped ribbon designs. The interlocking cylinder design did not cause similar motion. When compared with the other two designs, the interlocking cylinder had significantly greater separation forces between coil pusher and coil while in the catheter. Frictional forces within the catheter were lower for the interlocking cylinder mechanically detachable coil design than for a commercially available conventional coil and coil pusher system. During in vivo testing, the mechanically detachable coil design operated smoothly in the catheter, providing good release and retraction in aneurysms and straight vessels.The interlocking cylinder mechanically detachable coil design is superior to the other two tested designs. The mechanically detachable coil was reliably delivered and detached in in vivo testing for the treatment of aneurysms and for the occlusion of blood vessels.

Abstract

To determine whether there is a physiologic explanation for the predisposition of patients with certain angiographic characteristics to symptoms of hemorrhage and steal.Superselective transcatheter feeding arterial pressure and mean arterial pressure measurements were obtained before embolotherapy in 32 patients with cerebral arteriovenous malformations. Pressures were correlated with previously described angioarchitectural characteristics predisposing to hemorrhage and steal. These included size of the arteriovenous malformation, feeding artery length, venous drainage pattern, and angiomatous change.The feeding arterial pressure and feeding arterial pressure/mean arterial pressure ratios were significantly decreased in patients with angiomatous change. Feeding arterial pressure and feeding arterial pressure/mean arterial pressure ratios progressively decreased as lesions went from peripheral, to mixed, to central venous drainage. A trend for lower feeding arterial pressure was also demonstrated with greater feeding pedicle length. A statistically significant correlation could not be demonstrated between feeding arterial pressure or feeding arterial pressure/mean arterial pressure ratios and size of the arteriovenous malformation, hemorrhage, or symptoms of steal.Feeding arterial pressure measurements help provide a physiologic basis for the relationship between certain angiographic characteristics and hemorrhage and steal symptoms in patients with arteriovenous malformation.

Abstract

The authors describe the use of intraarterial papaverine to treat vasospasm following subarachnoid hemorrhage. Two cases are reported: a 40-year-old woman with a posterior communicating artery aneurysm and a 67-year-old man with a posterior cerebral artery aneurysm. Both patients developed symptomatic, angiographically demonstrated vasospasm that responded to papaverine infusion.

Abstract

Previous reports of embolization of cerebral arteriovenous malformations (AVMs) have evaluated the technique as adjunctive therapy prior to surgery or radiosurgery; our aim is to assess the role of embolization following radiosurgery.Six patients previously treated with radiosurgery and showing no response as judged by cerebral angiography were embolized 24 to 55 months (mean 34.3 months) after initial radiosurgery.In five of six, a significant volume reduction was achieved ranging from 60%-100% (mean 74%). One patient was treated with embolization alone and the AVM has remained fully thrombosed 2 years after treatment. Three patients underwent surgical resection for cure after embolization, and two patients had repeat radiosurgery to a significantly smaller AVM volume. One patient had an asymptomatic carotid dissection at embolization; however, no clinically apparent complications occurred in the treatment group.Embolization can be used after radiosurgery to assist in the management of those AVMs that have not responded to initial treatment.

Abstract

Magnetic resonance imaging (MRI) was used to study in vivo the brains of 49 patients with chronic alcoholism, 3 to 4 weeks post-withdrawal, and 43 normal healthy controls, all right-handed male veterans between the ages of 23 and 70 years. MRI scans were analyzed using a semi-automated procedure, which allowed the subcortical regions to be segmented into cerebrospinal fluid (CSF) and brain tissue and the cortical regions to be segmented into CSF, gray matter, and white matter. An age regression model was used to examine the effects of alcohol on brain structure, over and above that expected from the normal aging process. The alcoholics exhibited decreased tissue and increased CSF after correcting for aging. In the cortex, there was significant loss of both gray matter and white matter volume. In this sample of alcoholics, no particular cortical region was preferentially affected or spared. Furthermore, brain tissue volume loss increased with advanced age in the alcoholics. In this group of alcoholics there was no relationship between length of illness and age, i.e., the younger alcoholics had as heavy alcohol use histories as did the older alcoholics. Thus, the increased brain tissue loss with advanced age is interpreted as evidence for age-related increase in brain vulnerability to chronic alcohol abuse.

Abstract

The authors describe a patient with complex cranial neuropathy caused by pathologically proved hypertrophic interstitial neuropathy. Plain and contrast-enhanced MR studies were performed prior to surgical exploration. Surgical complications caused the patient's death and a complete pathology study was done. Though nonspecific, MR proved helpful in determining the extent of disease and areas of anatomic involvement.

Abstract

Patients with cerebral arteriovenous malformations (AVMs) have an increased risk of hemorrhage if an intranidal aneurysm is present. Angiograms from 125 patients with cerebral AVMs were evaluated, and 15 (12%) had intranidal aneurysms. All 15 patients had a history of bleeding. Five patients underwent particulate or liquid embolization before surgical excision of or radiation therapy for the AVM. All aneurysms were thrombosed at the time of embolization. Ten patients underwent radio-surgery alone. Eight of the 10 underwent angiographic follow-up (mean, 33 months); seven patients showed complete obliteration of the AVM without residual aneurysm. Histologic evaluation showed intranidal aneurysms to be thin-walled vascular structures, and they are the likely site for AVM hemorrhage. Embolization is an effective method for achieving thrombosis of the intranidal aneurysm and may be beneficial in patients undergoing radiation therapy because of a long latency period between treatment and thrombosis of the AVM.

Abstract

The case history of an infant with a large gliofibroma is presented. Gliofibromas are rare mixed glialmesenchymal tumors that have been poorly characterized. The computerized tomography appearance and a detailed light and electron microscopic description are presented, along with immunoperoxidase studies of this tumor. This case is compared with gliofibromas described elsewhere in the literature.

Abstract

We report an unusual case of inflammatory pseudotumor of the choroid plexus of the right lateral ventricle, manifesting as an intraventricular mass and causing unilateral hydrocephalus in a 48-year-old man who suffered from Sjögren's disease and subacute cutaneous lupus erythematosus. The lesion obliterated the normal choroidal architecture by a mixed chronic inflammatory process that was associated with reactive connective tissue changes. Immunohistochemical studies showed no light-chain restriction in the cells, and residual islands of transthyretin-positive epithelial cells were identified, implicating the choroid plexus origin of the mass.

Abstract

Thirteen patients have been treated over a 2-year period utilizing a team approach between the radiology and surgical services. Initial diagnostic evaluation is directed at determining the size and anatomic extent of the hemangioma; clinical assessment of coagulation and hemodynamic status is also performed. Arteriography with superselective embolization precedes the surgical procedure, usually by 24 hours. The YAG laser with contact sapphire-tip scalpels is then utilized for resection and reconstruction of the hemangioma. Total removal of hemangioma was achieved in 9 of 13 patients, and partial or subtotal removal was achieved in the remainder. Blood loss and complications were minimal.

Abstract

In patients with intracerebral arteriovenous malformations (AVMs), symptoms attributed to steal can lead to progressive debilitating deficits. This study was undertaken to determine which morphologic features of the AVM could be correlated with clinical symptoms of steal. Over a 4-year period, 65 patients with intracranial AVMs were evaluated with angiography supplemented by MR (46 cases) and CT (19 cases). Eleven characteristics of AVM vascular architecture were studied; these included size, lobar location, periventricular/intraventricular location, arterial stenosis, arteriovenous fistulae, angiomatous change (the presence of dilated transcortical collateral circulation), venous drainage pattern (central, cortical, mixed), venous stenosis, venous aneurysm or ectasia, venous variation, and delayed drainage. These characteristics were correlated with a history of clinical steal, which was seen in nine (14%) of 65 patients. Three characteristics were found to correlate highly with steal: angiomatous change (p less than .0001), size (p less than .0001), and peripheral venous drainage (p = .045). The mean size of the AVM nidus was 31.3 cm3 for the entire group of patients, 105.0 cm3 for patients with steal, and 19.5 cm3 for those without steal symptoms. Angiomatous change was seen in six (9%) of 65 patients; all six of these had clinical steal. The association of clinical steal with AVM size, angiomatous change, and peripheral venous drainage may contribute to establishing a prognosis and treatment planning. When a patient's symptoms are caused by steal, treatment with subtotal excision or partial embolization may be beneficial.

Abstract

The most serious and frequent complication of intracranial arteriovenous malformations (AVMs) is intracranial hemorrhage. Identification of patients at greatest risk for intracranial bleeding would be beneficial. Detailed analysis of vascular architecture was performed in 65 patients with intracranial AVMs to identify the vascular characteristics that correlated with hemorrhage. Fifteen characteristics were assessed. Hemorrhage was present in 45 patients (69%). The following characteristics correlated positively with hemorrhage (Fisher-Irwin exact test): central venous drainage (P less than .0001), periventricular or intraventricular location of the AVM (P = .0002), and intranidal aneurysm (P = .028). The following characteristics correlated negatively with hemorrhage: angiomatous change (P = .0005), peripheral venous drainage (P = .005), and mixed venous drainage (P = .021). Multivariate linear discriminant analysis demonstrated that central venous drainage, angiomatous change (negatively predictive), intranidal aneurysm, and periventricular or intraventricular location of the AVM were the most discriminating or predictive characteristics of hemorrhage. Detailed analysis of the vascular architecture of intracranial AVMs helped identify features that strongly correlate with clinical hemorrhage and have important prognostic implications for the treatment of patients with these lesions.

Abstract

Twenty patients with capillary/cavernous hemangiomas of the periorbital area (eyelid, eyebrow, nose extending to canthus) have been treated with a variety of techniques. Six patients were treated by yttrium-aluminum-garnet (YAG) laser photocoagulation and direct injection of steroids. Rapid shrinkage of the hemangiomas occurred in all patients, and 2 infants whose eye was totally occluded by the hemangioma had their eyes rapidly opened. YAG laser excision with or without previous photocoagulation plus injection and with arteriogram plus superselective embolization was performed in the other 14 patients. Results were satisfactory in all patients.

Abstract

Differentiation of benign from pathologic compression fractures of vertebral bodies was evaluated with magnetic resonance imaging in a prospective study of 53 patients. Twenty-six patients had 34 benign posttraumatic compression fractures. Twenty-seven patients had metastatic disease to the vertebral column and seven pathologic fractures. T1- and T2-weighted spin-echo (SE) sequences (1.5 T) were performed in all patients. A presaturation technique was used to obtain "fat" and "water" images to better assess the degree of normal fatty marrow replacement in fractured vertebrae. Short inversion-time inversion-recovery (STIR) images were also obtained. Discrimination between benign and pathologic compression fractures was generally possible with the SE sequences. Chronic benign fractures demonstrated isointense marrow signal intensity (SI), compared with that of normal vertebrae with all sequences. Pathologic fractures showed low SI on T1-weighted images and high SI on T2-weighted images. Fat images revealed complete replacement of normal fatty marrow, shown as absent SI in the involved vertebral body. Water and STIR images showed diffuse high SI in pathologic fractures, with STIR images having the highest contrast between abnormal and normal marrow. Acute benign compression fractures also demonstrated high SI on T2-weighted, water, and STIR images, but the SI was less pronounced and the pattern was generally more inhomogeneous than that of pathologic compressions. In general, fat images showed only partial replacement of normal fatty marrow by low SI, in contrast to the complete absence of marrow SI typical of pathologic fractures.

Abstract

A massive cavernous hemangioma of the face in an 11 month old child has been successfully resected utilizing a combination of laser and non-laser techniques. The hemangioma was initially treated twice with YAG laser photocoagulation plus direct injection of steroids. This treatment promptly stopped the rapid growth and induced blanching as well as a 25% shrinkage with each treatment. Arteriogram with superselective embolization produced a further shrinkage of the hemangioma. Finally, the contact YAG laser with sapphire scalpel tips was utilized for complete and cosmetically satisfactory hemangioma resection. The treatment of a massive cavernous hemangioma by a combination of modalities is discussed.

Abstract

For 4 months, a prototype digital subtraction system was used to obtain images of the cerebral vasculature after intraarterial contrast injections. In 12 instances, the intraarterial injections were recorded with both a digital subtraction unit and conventional direct magnification film-screen system. The digital subtraction and conventional film subtraction images were compared and graded for quality and information content by three skilled observers. In addition, quantitative measurements of contrast-detail performance and spatial resolution were obtained on both the digital system and the screen-film imaging chain. In a clinical setting, both the digital subtraction and conventional film-screen systems provided similar quality images and angiographic information. Contrast-detail curves demonstrated that digital subtraction angiography outperformed conventional film technique for low-contrast objects. Digital subtraction angiography also reduced the time required to obtain the angiogram, markedly reduced film cost, and lowered the contrast agent burden.

Abstract

This retrospective study investigated the possible adverse effects of cancer therapy on the brain. Cranial computed tomographic scans of 76 patients with non-central nervous system malignancies and 25 patients with leukemia had enlarged lateral ventricles and/or cortical sulci in 19% and 40%, respectively. Leukemic patients, especially those with meningeal involvement, had the most frequent and most severe abnormalities.

Abstract

Computerized tomographic scans were performed on 31 patients with primary diseases of the white matter. Among 18 patients with multiple sclerosis, acute lesions were visualized in five, all with symptomatic cerebral hemisphere disease. Characteristic white matter lesions were also demonstrated in adrenoleukodystrophy, spongiform encephalopathy, progressive multifocal leukoencephalopathy, disseminated necrotizing leukoencephalopathy, and an undiagnosed leukoencephalopathy associated with malignancy. Besides identifying white matter abnormalities, the CT scan patterns were often specific enough to help distinguish among the various etiologic possibilities for the abnormalities. Useful diagnostic characteristics included the anatomic distribution of lesions, mass effect, atrophic changes, and enhancement after contrast infusion.

Abstract

On computerized tomography scanning, two patients with adrenoleukodystrophy had low-density abnormalities in the parieto-occipital lobes, which enhanced anteriorly with contrast infusion. Computerized tomographic correlation with the published pathology is discussed. CT scanning may be an important diagnostic procedure in the early diagnosis of adrenoleukodystrophy.

Abstract

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the central nervous system which predominantly affects immunologically compromised hosts. The distinctive CT appearance in three documented cases includes low-density lesions of central and convolutional white matter with scalloped lateral borders. Lesions demonstrate no mass effect or contrast material enhancement. Findings are discussed with reference to other entities which may produce a similar CT appearance.

Abstract

Four patients with anorexia nervosa were studied by cranial computed tomography (CT). Three of the four demonstrated abnormal enlargement of cortical sulci and subarachnoid spaces as compared with an age-matched control group. The relationship of this finding to established neuropathological changes in anorexia nervosa is discussed.

Abstract

Two patients with orbital involvement of plasma cell myeloma are presented. The first patient presented an isolated plasmacytoma in the orbit; the second patient had generalized plasma cell myeloma. In both cases X-rays and computed tomographic scanning gave valuable information and biopsy confirmed the diagnosis.